It’s predicted that fraudsters will use the run up to Christmas – which now starts during the Black Friday shopping period following American Thanksgiving Day – to sneak through defenses.

Some 50 million global online fraud attacks are expected over the Black Friday and Cyber Monday shopping week.

“It’s not that fraudsters expect IT teams to take their eye off the ball, but they are opportunists, so are looking to take advantage of periods where their fraudulent transactions are less likely to be spotted,” ThreatMetrix product and data evangelist, Rebekah Moody, told Infosecurity.

This is the case because basket values are traditionally higher this time of year, meaning fraudsters will try to sneak through higher value transactions in the hope of not being spotted.

Transaction volumes are also set to peak, so retailers often lower their risk tolerance to let more through without the added friction of fraud checks, explained Moody.

One of the main ways cyber-criminals are circumventing traditional fraud filters is by using automated bots.

“These have evolved from being the traditional brute force attacks that were traditionally stopped by WAFs,” she added. “They’re now much cleverer, adopting low and slow attack rate patterns to masquerade as legitimate human traffic. They might even sneak in a good transaction to trick the system as they mass test and validate stolen identity credentials harvested from data breaches.”

Another tactic which retailers may find hard to combat is when the cyber-criminal socially engineers a victim into downloading remote access software on their machine. Because they take over the account after the customer has legitimately logged in there are no unusual patterns for the retailer to spot.

Fraud prevention systems conducting behavioral analysis of users can help to spot bots and sudden changes in behavior that could indicate an account takeover, Moody claimed.